Impairment of Intrinsically Photosensitive Retinal Ganglion Cells Associated With Late Stages of Retinal Degeneration

Purpose. To evaluate quantitative and qualitative age-related changes in intrinsically photosensitive melanopsin-containing retinal ganglion cells (ipRGCs) in transgenic P23H rats, an animal model of autosomal dominant retinitis pigmentosa (RP) was examined. Methods. ipRGC density, morphology, and integrity were characterized by immunohistochemistry in retinas extracted from P23H and Sprague–Dawley (SD) rats aged 4, 12, and 18 months. Differences between SD and P23H rats throughout the experimental stages, as well as the interactions among them, were morphologically evaluated. Results. In rat retinas, we have identified ipRGCs with dendrites stratifying in either the outer margin (M1) or inner side (M2) of the inner plexiform layer, and in both the outer and inner plexuses (M3). A small group of M1 cells had their somas located in the inner nuclear layer (M1d). In SD rats, ipRGCs showed no significant changes associated with age, in terms of either mean cell density or the morphologic parameters analyzed. However, the mean density of ipRGCs in P23H rats fell by approximately 67% between 4 and 18 months of age. Moreover, ipRGCs in these animals showed a progressive age-dependent decrease in the dendritic area, the number of branch points and terminal neurite tips per cell, and the Sholl area. Conclusions. In the P23H rat model of retinitis pigmentosa, density, wholeness, and dendritic arborization of melanopsin-containing ganglion cells decrease in advanced stages of the degenerative disease.

Adsorption and first stages of polymerization of aniline on platinum single crystal electrodes

The present communication studies the adsorption of aniline on platinum single crystal electrodes and the electrochemical properties of the first layers of polyaniline(PANI) grown on those platinum surfaces. The adsorption process was studied in aqueous acidic solution (0.1 M HClO4) and the electrochemical properties of thin films of PANI in both aqueous (1 M HClO4) and non-aqueous media (tetrabutyl ammonium hexafluorophosphate (TBAPF6) with additions of methanesulphonic acid in acetonitrile). First of all, it was found that the adsorption of aniline on platinum single crystal surfaces is a surface sensitive process, and even more important that the adsorption features found at low concentrations (5 × 10−5 M) can be directly correlated to the electrochemical properties of thin films of PANI in the very early stages of polymerization. The Pt(1 1 0) surface was found to be more suitable to obtain polymers with more reversible redox transitions when studied in aqueous media (1 M HClO4). This is in good agreement with the higher polymerization rates found on this surface compared to Pt(1 0 0) and Pt(1 1 1). Finally the differences in ionic exchange rate were greatly enhanced when they were studied in organic media. The AC 250 Hz response in the case of the thin films synthesized on Pt(1 1 0) is about twice greater than that obtained in the other basal planes using polymer layers with the same thickness.

Retrieval of phenological stages of onion fields during the first year of growth by means of C-band polarimetric SAR measurements

The phenological stages of onion fields in the first year of growth are estimated using polarimetric observables and single-polarization intensity channels. Experiments are undertaken on a time series of RADARSAT-2 C-band full-polarimetric synthetic aperture radar (SAR) images collected in 2009 over the Barrax region, Spain, where ground truth information about onion growth stages is provided by the European Space Agency (ESA)-funded agricultural bio/geophysical retrieval from frequent repeat pass SAR and optical imaging (AgriSAR) field campaign conducted in that area. The experimental results demonstrate that polarimetric entropy or copolar coherence when used jointly with the cross-polarized intensity allows unambiguously distinguishing three phenological intervals.